Genetics Flashcards
Which technique is best suited to monitor viral load (RNA) in blood
polymerase chain reaction
What is currently considered the first genetic investigation of choice for an inherited disorder associated with developmental delay and learning difficulties
chromosomal microarray analysis as this has greater resolution than a karyotype
What is the most likely explanation for a woman being affected by an x-linked mutation that they are a carrier of
skewed x-inactivation
What is the best technique to identify a balanced translocation mutation
karyotyping - a chromosomal microarray cannot detect balanced chromosome translocations
what is the significant advantage of using DNA technology to identify bacteria from a patient sample using its 16s gene sequence
this allows identification of microbes that cannot be grown under normal laboratory conditions
Analysis of transcripts within bone marrow cells from a haematology department focuses on what material
RNA
What is the best technique for testing multiple genes for single base variants
next generation sequencing
What is the sequence of events that occurs during transcription
RNA polymerase binding
DNA chain separation
Transcription initiation
Elongation
Termination
What can chromosomal microarray testing be used to identify
Unbalanced chromosomal alterations
When is conventional cytogenetic used
to investigate a suspected balanced chromosomal translocation
What is the first step in the central dogma of making a protein from a gene
transcription
What is the most likely explanation for why a single base mutation in an exon has no effect on protein sequence
codon usage shows redundancy
If someone possesses a gene mutation and a health condition but their son has the mutated gene without the health condition, what is the most likely explanation
The mutation has variable penetrate
Why does next generation sequencing of genes have an advantage over conventional sequencing
it allows sequencing of a much larger number of genes
Why is aCGH preferred over karyotyping as a first test for chromosomal analysis
it is high resolution
What characteristic of a cancer cell is central to it acquiring new characteristics
genomic instability
What is the best first lien investigation for detecting unbalanced chromosomal rearrangements
aCGH
What is penetrance
the likely hood of having a disease if you possess the gene mutation
What karyotype can be identified in someone diagnosed with Turner syndrome
45 X - this syndrome affected females only
How many hydrogen bonds from between cytosine and guanine
3
How many hydrogen bonds form between adenine and thymine
2
In what ways can DNA be damaged during replication (3)
DNA strand breaks
Chemical cross-linking
Mismatched bases
What is a polymorphism
A change in the genome that does not cause a disease in its own right, but can predispose an individual to a common disease
What pattern of inheritance do classic genetic disease cause
Mendelian inheritance
Describe multi factorial diseases
when multiple polymorphisms cause risk of diseases
What is a missense mutation
a point mutation that causes a change to a single amino acids
Substitution
What is a nonsense mutation
one resulting in a premature stop codon: the polypeptide will be shorter
What are the possible types of insertion/deletion mutations (2)
In frame
Out of frame
Which type of insertion/deletion mutation causes a frame shift
out of frame
What is the result of promoter and splice site sequence changes (2)
terminates transcription or abnormal splicing
Balanced chromosome rearrangement
when all chromosomes are present after rearrangement
Unbalanced chromosome rearrangement
when some of the chromosomes/parts of chromosomes are missing after rearrangement
Causes major developmental problems/miscarriages
Aneuploidy
whole extra or missing chromosome
Which type of aneuploidy is better tolerated and why
X chromosome aneuploidy
Due to x inactivation
What is the definition of translocation
rearrangement of chromosomes
What is robertsonian translocation
when two acrocentric chromosomes are stuck end to end
reciprocal translocation
two broken off chromosome pieces from non-homologous chromosomes are exchanged
What chromosome is associated with Down’s syndrome
21
Which chromosome is associated with miscarriage when mutated
14
Which chromosome is associated with Edward’s syndrome
18
What is the karyotype of Klinefelter syndrome
47 XXY
What is FISH
a technique that uses fluorescent probes that bind only to parts of a nucleic acid sequence with a high degree of sequence complementarity
Can be used in genetic counselling
Each human has how many pairs of chromosomes
23
Which chromosome looks like a teddy bear
22
What is the short arm of a chromosome represented by
P
What is the long arm of a chromosome represented by
q
What is a meta centric chromosome
a chromosome whose arms are both roughly the same length
What is an acrocentric chromosome
a chromosome whose p arm is so short it is hard to observe
What is a telomeric chromosome
a chromosome whose centromere is located at the terminal end of the chromosome
What is monosomy
when there is a missing chromosome from one pair
What is trisomy
When there is an extra chromosome in a pair
Monosomy of the sex chromosome causes what
Turner’s syndrome
Describe the inheritance of mitochondrial disease
the diseased mitochondria is passed from mother to child
What is mosaicism
when cells within the same individual have different genetic makeup
What is epigenetic variation
functional modifications to the genome
What does methylation inhibit
DNA transcription
What is imprinting
when variations occur in gene expression depending on which parent you inherit the gene from
What is heteroplasmy
when different daughter cells contain different proportions of mutant mitochondria
How many copies of the tumour suppressor gene are required to be mutated for cancer to occur
two copies
